
import java.util.Scanner;
public class Test28 {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        double x=scanner.nextDouble();
        double result;
        if(x>0){
            result = 1/x;
        }else if(x==0){
            result = 0;
        }else {
            result = -1/x;
        }System.out.printf("f(%.1f)=%.1f\n",x,result);
        scanner.close();
    }
}